Bungled testimony by a key state witness brought the murder trial of Richard McTear, accused of killing a baby, to an abrupt halt Monday afternoon, as a judge sent jurors home while he decides whether to declare a mistrial.

McTear, 25, is charged with first-degree murder, aggravated child abuse and other offenses in the 2009 death of Emanuel Murray, a 3-month-old who prosecutors say was flung by McTear from a car on Interstate 275.

The child's mother, Jasmine Bedwell, now 22, took the stand on the first day of testimony Monday to describe how McTear, her ex-boyfriend, attacked her and inflicted fatal injuries on her baby. Emanuel's father was another man, who was in state prison at the time of the baby's death.

Under questioning from Hills­borough Assistant State Attorney Ron Gale, Bedwell said McTear, in a phone call, had "told me that he was going to come over and shoot my baby in the face and p--- on him … and he was going to kill both of us."

It was an accusation the court had ruled would not be introduced at trial after defense attorneys argued — and prosecutors agreed — last year that it was irrelevant. Bedwell previously said that threat took place about six weeks before the baby's death, and the court determined her allegation was out-of-bounds during extensive pretrial litigation that laid the rules for admissible evidence.

McTear's attorney, Assistant Public Defender Mike Peacock, immediately moved for a mistrial after Bedwell spoke.

"It clearly was the obligation of the state to make sure that their witnesses were aware of all orders with regard to testimony," Peacock said, asserting there was "absolutely nothing" that could be said to the jury to reverse the statement's prejudicial effects.

Hillsborough Circuit Judge William Fuente, visibly frustrated, said he was "on the horns of a dilemma" about how to proceed in the case, which has already consumed four years of the court system's time.

"As you all know, we spent a lot of time — a lot of time — on this case," Fuente said. "I'm going to send the jury home, and I'm going to ask the lawyers to research this to see what they can do."

He added, "One of the remedies is to grant a mistrial and start this all over again."

A mistrial ruling would reset the case to jury selection. That could still result in a significant delay, since it took five days and a pool of hundreds of potential jurors to empanel the current jury. Such factors typically require advance scheduling and must be coordinated with other cases on a judge's calendar.

Fuente told the attorneys to return to court today.

The State Attorney's Office declined to comment on the case's developments Monday.

Soon after Bedwell took the stand, Gale asked about her phone calls with McTear, asking: "What was the nature of those conversations?"

Gale later told Fuente that he did not anticipate she would bring up the alleged threats, though he acknowledged the testimony was "clearly … a violation" of the earlier agreement.

"That was not the answer I expected Ms. Bedwell would give to this question," Gale said.

Tampa criminal defense lawyer Lyann Goudie, a former prosecutor, said unwanted outbursts by state's witnesses are a common hazard.

"As a prosecutor, it happens a lot that you'll meet with someone and you say, 'Don't talk about this,' and they get up there and they say it," she said.

In McTear's case, Goudie said, it is doubtful that Bedwell's words can be remedied short of a mistrial declaration.

"If there was a specific order to keep that alleged prejudicial statement out, I don't think there's any curative instruction you can give in the case," she said.

Close adherence to proper procedures is especially important because McTear could face the death penalty if convicted, bringing scrutiny to how the trial was conducted during an appeal.

The trial's interruption came after opening statements in the morning, when Gale added new layers of detail to a grisly case.

Gale asserted that McTear, who at the time was 21, flew into a rage on the morning of May 5, 2009, after seeing Bedwell, who at the time was 17, returning to her home with another man who also was not the baby's father.

After attacking Bedwell, McTear poured a can of soda in her baby's face, Gale said. When Emanuel began to cry, Gale said, McTear picked up the car seat in which the child rested and hurled it across the room.

Emanuel was later found by the side of Interstate 275 near Fowler Avenue. Gale said the child had "road rash" injuries likely caused by being thrown from a moving car.

However, it was not those injuries that killed the baby, Gale said, but "severe and multiple skull fractures" that could not have come from being flung from a car, even at high speed.

Assistant Public Defender Mike Peacock suggested that the narrative advanced by police and prosecutors is not airtight. For instance, he said authorities have not clearly explained how Emanuel sustained his fatal injuries.

"The state would have you believe that the search for the truth is an easy process, but sometimes it's not an easy process," Peacock said.

Peter Jamison can be reached at pjamison@tampabay.com or (813) 226-3337. Follow him on Twitter @petejamison.